I am running JDK 1.7 & Windows 7 using netbeans 7.2 I have generated a SSH private & public key pair (SSH2-2048 bits) using putty-keygen. I do not have any password
Perhaps not a solution for you, but I found this question when I searched for my issue.
I had accidentally given the path to the public keyfile when JSCH expected the private keyfile.